package main

import (
	"time"
	"fmt"
)

func main() {
	fmt.Println("开始")
	go func() {
		for {
			fmt.Print(1)
		}
	}()
	go func() {
		for {
			fmt.Print(2)
		}
	}()
	go func() {
		for {
			fmt.Print(3)
		}
	}()
	time.Sleep(time.Second)
	fmt.Println("结束")
}